Conventionally, a separation method for separating a target component from a fluid to be processed is known. For example, an example of such a separation method is disclosed in the following Patent Document 1.
In the following Patent Document 1, a method of separating and recovering CO2 as a target component from a CO2 containing gas (an exhaust gas) as a fluid to be processed by causing CO2 to be absorbed into an absorption liquid from the CO2 containing gas is represented. Then, in the following Patent Document 1, in order to implement the separation and recovery method, a CO2 recovery device with an absorption tower for absorbing CO2 in the CO2 containing gas into the absorption liquid is used. In the absorption tower of the CO2 recovery device, while the CO2 containing gas is introduced into the absorption tower from the lower part of the absorption tower, the absorption liquid is introduced into the absorption tower from the upper part of the absorption tower, and the CO2 containing gas going up within the absorption tower and the absorption liquid going down from the upper part are brought into countercurrent contact with each other, thereby CO2 is absorbed into the absorption liquid from the CO2 containing gas.
Within the absorption tower used in the conventional separation and recovery method, heat of absorption is produced by absorption of CO2 into the absorption liquid from the CO2 containing gas, thereby increasing the temperature of the absorption liquid. When the temperature of the absorption liquid increases, the absorbed amount of CO2 per unit liquid amount of the absorption liquid decreases, and as a result, separation efficiency of CO2 is decreased. If trying to supplement the decrease in separation efficiency, the amount of the absorption liquid in contact with the CO2 containing gas needs to be increased. In that case, the absorption tower must be increased in size, and as a result, the separation device is increased in size.